1. Field of the Invention
This invention is related to electrical connectors. More specifically this invention is directed to sealed electrical connectors in which significant mating force must be overcome.
2. Description of the Prior Art
Electrical connectors of the type used in automotive and other applications quite often employ a large number of terminals and are often sealed. Many electrical connectors of this type employ a peripheral gasket seal at the mating interface between male and female connectors. A common example of electrical connector assemblies of this type consist of a first connector attached to a wire harness that is mated with a shrouded printed circuit board header. The first connector has a peripheral elastomeric seal that surrounds the mating side of the connector housing. When the first connector is mated to the printed circuit board header, the peripheral elastomeric seal engages the inner surface of the header shroud. The seal slides along this mating surface until the two connectors are fully mated.
Connectors of this type typically exhibit a relatively high mating force. Assembly specifications include maximum mating force requirements that are chosen to prevent damage to the connectors or terminals during mating and to insure that an operator can easily and reliably mate the two connectors. One approach to overcoming high mating force is to employ a cam slide connector. Cam slides are used to increase the force available to mate two electrical connectors, especially electrical connectors containing a large number of mating contacts or terminals. U.S. Pat. No. 5,478,251 is an example of a plug connector that uses a laterally shiftable cam slide that includes cam slots which engage cam follower pins. U.S. Pat. No. 5,618,194 is another example of an electrical connector that includes a laterally shiftable cam slide. Prior art connectors of this type have been used to connect automotive wiring harnesses to components in motor vehicles. For example, a cam slide connector of this type could be employed as part of an anti-lock braking system of the type shown in U.S. Pat. No. 5,766,026.
Although cam slide and other mechanical assist connectors do provide one means for overcoming high mating forces, there is a practical limit to the mechanical advantage that can be obtained by such devices. For sealed connectors, the mating force is due not only to the force required to mate male and female terminals. There is also a mating force component that is due to piston effect created as air or gas is trapped as the peripheral seal initially engages the header shroud or other female mating surface. The trapped air is compressed while the two connectors move closer together. The volume in which this air is trapped is reduced, the pressure is greater and the mating force is increased. Indeed for most if not all applications, this mating force component due to the compression of trapped air is a significant component of the overall mating force. One prior art approach to reducing this mating force component is to bleed air as the two connectors are mated. An example of this approach is shown in U.S. Pat. No. 5,358,420, in which the connector includes a groove on the interior surface of the connector shroud. This groove permits pressure relief during mating. However, only a small groove can be employed, thus limiting the amount of pressure relief that is possible. A larger groove could damage the seal or limit the effectiveness of the seal.